Leak-resistant dry cell



April 20, 1965 T. A. REILLY 3,179,537-

LEAK-RESISTANT DRY CELL Filed May 1. 1961 POROUS i CARBON 23 ELECTRODE20 26 IMPREGNATED RBON {5 {a ECTRODE IMPREGNATED CARBON ELECTRODEINVENTOR. THOMAS A. REILLY United States Patent 3,179,537 LEAK-RESISTANTDRY CELL Thomas A. Reilly, Cleveland, @hio, assignor to Union CarbideCorporation, a corporation of New York Filed May 1, 1%1, Ser. No.106,769 12 Claims. (Ci. 136-133) This invention relates toleak-resistant dry cells of the type having a closed containersurrounding the cell proper.

The so-called Leclanche dry cell used for flashlights, portable radios,photoflash and other devices has gone through an evolution ofimprovements during the past decade or more in an attempt bymanufacturers to prevent leakage from the cell during and after its use.Despite the many proposals, however, that have been advanced, therestill remains a need for a better leak-resistant dry cell.

One proposal that has been adopted commercially is to encase aconventional dry cell within a closed container. This dry cellconstruction, however, has been plagued by certain difficulties. Forexample, one type of container which has been used comprises a metalcontainer, but this suffers from the disadvantage that the metal issubject to corrosion by liquid exudate from the cell. To avoid thisdisadvantage, non-corrodible containers have also been utilized. Theprincipal difliculty, however, with non-corrodible containers is thatthey do not possess the mechanical strength of metal containers andsuffer from the disadvantage that they may often be damaged, and evendestroyed, by the pressure which builds up from the formation of gaswithin the cell. Several suggestions have been advanced for overcomingthis disadvantage of non-corrodible containers in which the attempt hasbeen made to continuously vent the gas from the cell. Thus, in priorconstructions, the gas has been vented, for example, through the carbonelectrode, and then out through venting means provided in the topclosure of the container. The difiiculty, however, with thesesuggestions is that the venting paths, for instance through the carbonelectrode, have been prone to obstruction by cell exudate, therebyblocking the passage of gas from the cell.

It is therefore an important object of the invention to provide animproved gas venting path in a leak-resistant dry cell particularly ofthe type of construction utilizing a non-corrodible container, which gasventing path is not prone to obstruction during use of the cell.

Briefly, the above and other objects are achieved by the invention whichcomprises a gas venting electrode of carbon embedded within thedepolarizer mix and protected against penetration of both liquid and gasbetween the depolarizer mix and the top closure of a leak-resistant drycell.

In the accompanying drawing:

FIG. 1 is a vertical elevation partially in section of a lealoresistantdry cell embodying the invention;

FIG. 2 is a similar view of the top portion only of a dry cell showinganother embodiment of the invention;

FIG. 3 is a similar view of another type of cell construction showingstill another embodiment; and

FIG. 4 is a view taken along the line 4 i of FIG. 3.

Referring to the drawing, a leak-resistant dry cell of a constructionotherwise conventional but embodying the invention is shown in FIG. 1.The cell comprises a cup electrode of a consumable metal, for instance,zinc having therein a porous carbon electrode 12 embedded within adepolarizer mix 14 and an immobilized electrolyte l6 suitable in theform of a conventional paste. At the top of the cell surrounding thecarbon electrode 12 within the free space between the top closure andthe depolarizer mix 14 and protecting the electrode 12 againstpenetration of both liquid and gas is a seal 18. The seal 18 is composedof a liquid and gas impermeable material, for ex- 3,179,537 PatentedApr. 20, 1965 ample, wax and preferably also underlies the top closurefor. added protection against leakage through. the closure. The seal 18may be achieved in a number of ways. For instance, the top closure priorto assembly of the cell may be provided with a layer of wax suflicientto form the seal. The top ClOSLllB after the cell has been assembled isthen heated slightly to cause some of the wax to flow down and aroundthe carbon electrode 12, hence sealing the electrode within the freespace below the top closure of the cell.

A preferred top closure for the cell comprises a flanged metal cap 20having gas venting means 22 therein fitted on top of the carbonelectrode 12 and an insulating washer 24 carried by the cap 20 on whichrests the inner peripheral edges of a metal washer 26 whose outer edgesare locked in engagement with a jacket 28. The jacket 2'8 isnon-corrodible, it being composed, for example, of paper, and fits thecup electrode 10 rather loosely, thereby providing a supplementarychamber 30 for receiving liquid exudate from the cell. Although notshown, the jacket 28 also secures a typical false bottom closure for thecell in contact with the bottom of the cup electrode 10.

During use of the cell, especially under severe conditions, gas isreleased. The gas follows a path from within the depolarizer mix 14through the porous carbon electrode 12 and then out of the cell throughthe top closure. At the same time, liquid is exuded through thedepolarizer mix 14- towards the cup electrode 10, hence there being noproblem of the liquid obstructing the passage of gas through the porouscarbon electrode 12 within the depolarizer mix 14, and eventuallycollects within the free space below the top closure. The seal 18protects the electrode 12 against penetration by liquid exudate evenunder the influence of gas pressure which may develop within the cell,the seal 18 being also impermeable to gas, hence preventing theliquidexudate from blocking the passage of gas through the electrode 12and out of the cell.

The construction described is characterized by the fact that a porouscarbon electrode is utilized for venting gas from a dry cell. Thisconstruction is simple and practical and for this reason generallypreferred. It is: entirely possible, however to construct a dry cellembodying the principles of the invention in which a gas ventingelectrode of impervious carbon is used.

Such a construction is shown in FIG. 2. As shown, a dry cell isconstructed with a hollow electrode 32 of carbon impregnated with Wax,for example, to render it impermeable to both liquid and gas. The hollowelectrode 32 has perforations 34 provided therein below the top of thedepolarizer mix 14 for venting gas through it and out of the cellthrough the top closure. It will be particularly noted that the gasenters the hollow electrode 32 from within the depolarizer mix 14 sothat there is virtually no opportunity for liquid to escape into theelectrode and block the passage of gas through the cell.

Another construction which may be used is shown in FIG. '3. Here, a drycell is constructed utilizing a hollow electrode 36 of carbon alsoimpregnated with wax, for example, but in this construction theelectrode is only partially embedded within the depolarizer mix 14. Afluted core 38 of carbon is inserted within the hollow electrode 36 andis also embedded within the depolarizer mix 14. This constructionachieves the same advantages provided for by the construction shown inFIG. 2, but differs in that gas venting takes place from within thedepolarizer mix 14 along the fluted core, 38 into the hollow electrode36 and out through the top closure of the cell. The top closure for thecell shown also differs from that illustrated in FIGS. 1 and 2 in thatthe closure is composed of a one-piece cover 39 of metal having similargas venting means 22.

A seal 40 suitably of wax is also preferably but not necessarilyemployed in the constructions illustrated in FIGS. 2 and 3. The seal 40as shown preferably differs somewhat from that shown in FIG. 1 in thatthe seal not only underlies the top closure but also covers the upperedges of the cup electrode exposed within the cell. This serves toprotect the cup electrode 10 from corrosion by the liquid exudate whichcollects within the free space above the depolarizer mix 14 during useof the cell.

It will be understood that many changes and modifications of the variousdry cell constructions described herein may be made without departingfrom the spirit and scope of the invention.

What is claimed is:

1. A leak-resistant dry cell comprising, in combination, a cup electrodeof a consumable metal containing depolarizer mix and electrolyte; aclosure for said cell having gas venting means therein, said closurebeing spaced from said depolarizer mix defining a free spacetherebetween for liquid in said cell; and a carbon electrode embeddedwithin said depolarizer mix and extending through said free space tosaid closure, said carbon electrode being sealed on at least thesurfaces thereof normally exposed within said free space with a liquidand gas impermeable material, whereby liquid is prohibited from passageinto and through said carbon electrode from said free space even underthe influence of gas pressure in said cell, said carbon electrode inconjunction with said gas venting means in said closure providing acontinuous, liquid free path for venting gas from said cell.

2. A leak-resistant dry cell comprising, in combination, a cup electrodeof a consumable metal containing depolarizer mix and electrolyte; a topclosure for said cell having gas venting means therein, said top closurebeing spaced from said depolarizer mix defining a free spacetherebetween for liquid in said cell; a porous carbon electrode embeddedwithin said depolarizer mix and extending through said free space tosaid top closure; and a liquid and gas impermeable seal adhered to andsurrounding the surfaces of said porous carbon electrode normallyexposed within said free space for prohibiting the passage of liquidinto and through said porous carbon electrode from said free space evenunder the influence of gas pressure in said cell, said porous carbonelectrode in conjunction with said gas venting means in said top closureproviding a continuous, liquid free path for venting gas from said cell.7

3. A leak-resistant dry cell as defined by claim 2 in which said seal iscomposed of wax.

4. A leak-resistant dry cell comprising, in combination, a cup electrodeof a consumable metal containing depolarizer mix and electrolyte; a topclosure for said cell having gas venting means therein, said top closurebeing spaced from said depolarizer mix defining a free spacetherebetween for liquid in said cell; and a hollow porous carbonelectrode embedded within said depolarizer mix and extending throughsaid free space to said top closure, said hollow carbon electrode beingimpregnated on the surfaces thereof normally exposed within said freespace with a liquid and gas impermeable material and having at least oneperforation disposed below the surface of said depolarizer mix forpermitting the passage of gas into and through said hollow carbonelectrode from within said depolarizer mix, said hollow carbon electrodein conjunction with said gas venting means in said top closure providinga continuous, liquid free path for venting gas from said cell.

5. A leak-resistant dry cell as defined by claim 4 in which a layer of aliquid and gas impermeable material is adhered to and surrounds thesurfaces of said carbon electrode normally exposed within said freespace of said ce 1.

6. A teak-resistant dry cell comprising, in combination, a cup electrodeof a consumable metal containing depolarizer mix and electrolyte; a topclosure for said cell having gas venting means therein, said top closurebeing spaced from said depolarizer mix defining a free spacetherebetween for liquid in said cell; a hollow porous carbon electrodeembedded a short distance below the surface of said depolarizer mix andextending through said free space to said top closure; said hollowcarbon electrode being impregnated on the surfaces thereof normallyexposed within said free space with a liquid and gas impermeablematerial and a fluted carbon core disposed within said hollow carbonelectrode and embedded within said depolarizer mix for providing apassage for gas into and through said hollow carbon electrode fromWithin said depolarizer mix, said hollow carbon electrode in conjunctionwith said gas venting means in said top closure providing a continuous,liquid free path for venting gas from said cell.

7. A leak-resistant dry cell as defined by claim 6 in which a layer of aliquid and gas impermeable material is adhered to and surrounds thesurfaces of said carbon electrode normally exposed within said freespace of said cell.

8. A leak-resistant dry cell comprising, in combination, a cup electrodeof a consumable metal containing depolarizer mix and electrolyte; ajacket surrounding said cup electrode; a top closure for said celllocked in engagement with said packet and having gas venting meanstherein, said top closure being spaced from said depolarizer mixdefining a free space therebetween for liquid in said cell; a porouscarbon electrode embedded within said depolarizer mix and extendingthrough said free space to said top closure; and a liquid and gasimpermeable seal of wax adhered to and surrounding the surfaces of saidcarbon electrode within said free space for prohibiting the passage ofliquid into and through said carbon electrode from said free space evenunder the influence of gas pressure in said cell, said carbon electrodein conjunction with said gas venting means in said top closure providinga continuous, liquid free path for venting gas from said cell.

9. A leak-resistant dry cell as defined by claim 8 in which said sealunderlies said closure.

10. A leak-resistant dry cell as defined by claim 8 in which said sealunderlies said closure and also overlies said cup electrode between saiddepolarizer mix and'said closure. 7

11. A leak-resistant dry cell as defined by claim 8 in which said jacketis non-corrodible.

12. A leak-resistant dry cellas defined by claim 8 in which said closureis composed of metal in one piece.

References (Iited by the Examiner UNITED STATES PATENTS 710,278 9/02Klinker et al. 1,196,225 8/ 16 Foos. 2,015,379 9/35 Deibel. 2,552,0915/51 Glover 136-121 2,704,780 3/55 MacFarland. 2,773,926 12/56 Glover136107 2,850,558 9/58 Urry 136-133 3,051,769 8/62 Jammet 1361333,090,824 5/63 Reilly et a1. 136107 FOREIGN PATENTS.

475,317 7/51 Canada.

1,216,672 11/59 France.

JOHN H. MACK, Primary Examiner.

JOHN R. SPECK, Examiner,

1. A LEAK-RESISTANT DRY CELL COMPRISING, IN COMBINATION, A CUP ELECTRODEOF A CONSUMABLE METAL CONTAINING DEPOLARIZER MIX AND ELECTROLYTE; ACLOSURE FOR SAID CELL HAVING GAS VENTING MEANS THEREIN, SAID CLOSUREBEING SPACED FROM SAID DEPOLARIZER MIX DEFINING A FREE SPACETHEREBETWEEN FOR LIQUID IN SAID CELL; AND A CARBON ELECTRODE EMBEDDEDWITHIN SAID DEPOLARIZER MIX AND EXTENDING THROUGH SAID FREE SPACE TOSAID CLOSURE, SAID CARBON ELECTRODE BEING SEALED ON AT LEAST THESURFACES THEREOF NORMALLY EXPOSED WITHIN SAID FREE SPACE WITH A LIQUIDAND GAS IMPERMEABLE MATERIAL, WHEREBY LIQUID IS PROHIBITED FROM PASSAGEINTO AND THROUGH SAID CARBON ELECTRODE FROM SAID FREE SPACE EVEN UNDERTHE INFLUENCE OF GAS PRESSURE IN SAID CELL, SAID CARBON ELECTRODE INCONJUNCTION WITH SAID GAS VENTING MEANS IN SAID CLOSURE PROVIDING ACONTINUOUS, LIQUID FREE PATH FOR VENTING GAS FROM SAID CELL.
 2. ALEAK-RESISTANT DRY CELL COMPRISING, IN COMBINATION, A CUP ELECTRODE OF ACONSUMABLE METAL CONTAINING DEPOLARIZER MIX AND ELECTROLYTE; A TOPCLOSURE FOR SAID CELL HAVING GAS VENTING MEANS THEREIN, SAID TOP CLOSUREBEING SPACED FROM SAID DEPOLARIZER MIX DEFINING A FREE SPACETHEREBETWEEN FOR LIQUID IN SAID CELL; A POROUS CARBON ELECTRODE EMBEDDEDWITHIN SAID DEPOLARIZER MIX AND EXTENDING THROUGH SAID FREE SPACE TOSAID TOP CLOSURE; AND A LIQUID AND GAS IMPERMEABLE SEAL ADHERED TO ANDSURROUNDING THE SURFACES OF SAID POROUS CARBON ELECTRODE NORMALLYEXPOSED WITHIN SAID FREE SPACE FOR PROHIBITING THE PASSAGE OF LIQUIDINTO AND THROUGH SAID POROUS CARBON ELECTRODE FROM SAID FREE SPACE EVENUNDER THE INFLUENCE OF GAS PRESSURE IN SAID CELL, SAID POROUS CARBONELECTRODE IN CONJUNCTION WITH SAID GAS VENTING MEANS IN SAID TOP CLOSUREPROVIDING A CONTINUOUS, LIQUID FREE PATH FOR VENTING GAS FROM SAID CELL.